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TROPICAL DEPRESSION ELEVEN DISCUSSION NUMBER 8
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT WED OCT 06 1999
DATA FROM THE AIR FORCE RESERVE HURRICANE HUNTER RELAYED AFTER THE
LAST ADVISORY SUGGESTS THE CENTER OF TROPICAL DEPRESSION ELEVEN HAS
RE-FORMED CONSIDERABLY TO THE NORTHWEST OF THE EARLIER FIXES. THE
CENTER IS POORLY DEFINED IN VISIBLE SATELLITE IMAGERY...SO IT IS NOT
CLEAR WHETHER THE CENTER IS STILL NEAR THE LOCATION SUGGESTED BY THE
AIRCRAFT. THE INITIAL POSITION IS A RE-LOCATION FROM THE PREVIOUS
ADVISORY...AND MORE RE-LOCATION MAY BE NECESSARY THIS AFTERNOON WHEN
THE NEXT AIRCRAFT INVESTIGATES THE CYCLONE.
THE INITIAL MOTION IS ASSUMED TO BE 315/4...WHICH IS THE 24 HOUR
MOTION. THE DEPRESSION IS AT THE WESTERN END OF A WEAKENING FRONTAL
TROUGH EXTENDING ACROSS CENTRAL FLORIDA AND THE GULF OF MEXICO...
AND WATER VAPOR IMAGERY SHOWS A LARGE MID/UPPER ANTICYCLONE MOVING
EASTWARD ACROSS TEXAS...LOUISIANA...AND THE NORTHWEST GULF. THE
LARGE SCALE GUIDANCE INDICATES THE ANTICYCLONE SHOULD CONTINUE
EASTWARD...ALLOWING THE CYCLONE TO TURN NORTH AFTER 36 TO 48 HOURS.
THE OFFICIAL FORECAST REFLECTS THIS AND IS QUITE SIMILAR TO THE
PREVIOUS PACKAGE AFTER THE RE-LOCATION IS ACCOUNTED FOR. AN
ALTERNATE SCENARIO IS THAT THE RIDGE MAY BE STRONG ENOUGH TO DRIVE
THE SYSTEM INTO THE MEXICAN COAST BEFORE ANY TURN CAN OCCUR. THE
POSSIBILITY OF THIS INCREASES IF THE CENTER IS FARTHER WEST THAN
CURRENTLY THOUGHT.
WHILE THE ASSOCIATED CONVECTION IS DISORGANIZED...THE CLOUD TOPS ARE
TO -80C AND THE UPPER LEVEL WINDS APPEAR GENERALLY FAVORABLE. IF THE
CYCLONE STAYS OFFSHORE...AND IF IT CAN BETTER SEPARATE ITSELF FROM
THE GULF SURFACE TROUGH...IT SHOULD BE ABLE TO INTENSIFY. SOME
STRENGTHENING IS FORECAST AFTER 36 HR ON THE PREMISE THAT BOTH OF
THOSE IFS WILL OCCUR.
THE STRONGEST CONVECTION REMAINS WEST OF THE CENTER...OVER EASTERN
MEXICO BETWEEN VERACRUZ AND TAMPICO. HEAVY RAINS SHOULD PERSIST OVER
PORTIONS OF EASTERN MEXICO UNTIL THE DEPRESSION EITHER MOVES AWAY OR
DISSIPATES.
BEVEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 06/1500Z 20.6N 95.6W 30 KTS
12HR VT 07/0000Z 21.0N 96.0W 30 KTS
24HR VT 07/1200Z 21.5N 96.5W 30 KTS
36HR VT 08/0000Z 22.2N 96.9W 30 KTS
48HR VT 08/1200Z 23.0N 97.0W 35 KTS
72HR VT 09/1200Z 25.0N 97.0W 40 KTS
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